Pluggable electric vehicles (EVs) are rapidly growing in popularity. To support these vehicles, electric vehicle charging stations (EVCS) are being introduced for use in homes, offices, and commercial locations. Initially these charging stations were no more than fancy plugs with a minimum of added functionality to ensure safe operation. The typical envisioned application was a wall mounted device located in the garage of a private home. There was no issue of the charging station needing to measure the energy provided to the vehicle. As pluggable electric vehicles have proliferated, different use scenarios have materialized. In many of these use scenarios, the user must be charged for the energy delivered to the vehicle. When these EVCSs are used in commerce, for example as a paid public refueling station or in a submetering situation where the energy used for vehicle charging receives a different rate from the utility, the EVCS must measure energy accurately so as to provide accurate information for a financial transaction (billing). Just as the gas pumps at filling stations are tested periodically to assure that the customer is being fairly charged, EVCS used in commerce will need to be tested for accurate delivery of electric energy.
Up to this point in time, existing technology developed for testing EVCS operation has been concerned with the communication protocols by which an EVCS exchanges information with an electric vehicle. US Patent Application Publication No. 2013/0346010 A1 by Schulz, for example, discloses a testing system enabled to provide verification signals in compliance with existing charging protocols. Current, voltage, charge sequence, and power levels received from the EVCS may be determined. However, these measures alone as disclosed by Schulz can only serve purposes of ensuring that the charging of the electric vehicle is working within an accepted performance envelope that is required by EV charging standards. For example, Schulz's current measurement devices assist in enabling the testing system to monitor power levels coming from the EV charger and to detect current leakages or other faults in the power provided to the charger testing system. This is important, for example, because determination of power levels ensures that an EVCS will not overwhelm and damage an EV battery with a higher rate of power delivery than it is designed to withstand. A simple analogy is a smartphone battery which, if directly connected to a standard wall outlet without its power adapter, would burn up and be destroyed. In this scenario, Schulz would be concerned with examining the power ratings of the adapter to verify the smartphone battery is not exposed to too strong a current, voltage, or instantaneous power level which would cause damage.
Though systems such as Schulz are relevant to ensuring the safe and protocol-compliant operation of an EVCS with an electric vehicle, they are deficient in addressing energy measurement and billing accuracy. Said differently, there remains a deficiency in the field for a system usable to verify whether EVCSs actually deliver a total amount of energy which they claim to deliver and for which they therefore bill a customer operating the EVCS to charge the battery of his or her EV.